Currently, various contents are sold. Those contents are sold, recorded on recording media such as CDs (Compact Discs), for example. Alternatively, contents can be purchased through the Internet. Examples thereof are a service which provides digital contents such as music songs on line from servers to terminal devices (EMD: Electronic Music Distribution), and an Electronic Commerce (EC) by which music CDs can be ordered on line and distributed.
Contents recorded on recording media are sometimes added with additional data such as electronic watermarks or advertisements. To promote use of these additional data, there has been a technique which makes special service available when additional data is used as a content is played back from a recording medium.    Patent Document 1: Jpn. Pat. Appln. Laid-Open Publication No. 2002-112012
Meanwhile, FM broadcast stations provide related information related to songs to be broadcasted, through the Internet. For example, a service of providing related information of songs being currently broadcasted (now-on-air), lists of songs broadcasted in past programs (on-air list), or the like.
In addition, there are a service of searching for contents such as songs through the Internet (distributed-song search service), a service of searching for CDs (CD search service), and the like. In these search services, information concerning a CD which complies with a search key, and information related to songs contained in the CD are returned as a search result.
By interconnecting these services, it is possible to promote use of the services. For example, a link may be added from a server providing related information to a server selling contents, so that users can smoothly move to a content sales service from a related-information providing service. Interconnections between plural services, conveniences for users of the services improve.
However, a simple interconnection between services cannot change the quality of a service to be utilized next, depending on the contents of a service which is utilized first. For example, in case of purchasing a CD based on related information of a song with use of a personal computer, there exists no system which allows users to receive a special service such as discount only when a distributed song or CD is searched from and purchased from related information of a song broadcasted in a specific time band in a specific program. There has been demand for a system by which the same discount service is provided when the CD is purchased in a shop.
The technique described in the Patent Document 1 utilizes contents and additional data both recorded on recording media, and does not interconnect services through a network.